Role of fall tillage: Cover crops can improve spring planting

With harvest in full swing across the Delta, farmers are focused on one thing: getting their crop out of the field and to the gin or elevator. But a lot of farmers who plan on having some form of conservation tillage program in 2003 will follow their combines and pickers with fall tillage and planting of a cover crop.

Cotton grower Tommy Gregory in Jones, La., has experimented with fall tillage and cover crops off and on for several years. He uses a mix of production systems, including stale seedbed, minimum-till, strip-till and conventional tillage.

Like a lot of Delta producers, he's always open to eliminating tillage where possible to lower production costs.

“On ground going into cotton, we like to re-form our beds in the fall because we can set up for furrow irrigation,” Gregory says. “As a rule, I'd rather do tillage in the fall than in the spring. It saves us a lot of time when we're trying to plant cotton.”

Gregory prefers a wheat cover crop ahead of both cotton and corn, saying it gives him protection against sand blasting, helps keep soil in place and builds up organic matter. “We tried rye, but it can be very hard to terminate if you let it get too big,” he says. “And we quit planting Austrian winter peas, because it's a legume and a host crop for reniform nematodes.

“Wheat, on the other hand, works well for us and is relatively easy to terminate.”

David Harris, who farms 2,100 acres of cotton near Senath, Mo., started experimenting with cover crops in 1992. The first few years, he would plant wheat in strips — usually four rows of wheat interspersed with 24 rows of cotton.

“This approach worked real well until we had wind blow in the wrong direction — right down the cotton rows,” Harris says. “We lost 40 acres of cotton in 45 minutes to sandblasting that year.”

Now, Harris plants a wheat cover crop in the middle of 38-inch cotton rows. “Normally, we shred cotton stalks, run a minimum-till cultivator, square up beds and plant wheat,” Harris says. “This area is known for some pretty wicked winds, usually around Mother's Day, and our soil is pretty sandy. It can cut young cotton to shreds very quickly.”

Besides providing protection from sand blasting, the wheat cover crop also shields the crop from cold winds early in the season and helps keep the soil warm. “I really believe that the cotton emerges and gets established faster because of the wheat cover in the row middles,” Harris says.

“It's not ‘never till’, it's ‘no-till,” says John Bradley, former University of Tennessee agronomist who is now a conservation tillage specialist with Monsanto. “There are some good, sound reasons for fall tillage, but it should be kept to a minimum and address specific needs and problems.”

Some of those needs and problems include eliminating soil compaction, matching row configurations, re-hipping and bedding up for cotton coming out of soybeans, facilitating furrow irrigation, straightening out rows and smoothing out rutted fields after harvest.

Two cautions, according to Bradley: work soil when it's dry to avoid destruction of soil structure, and when re-bedding for cotton, try to rip, hip and roll in a single trip across the field. “The ultimate goal for spring is to be able to focus on a burndown herbicide application, start clean and get your crop planted,” he says.

Fall tillage can also be used to incorporate a cover crop, something more farmers might be considering this fall due to the amount of replanting necessary last spring because of wind and sand damage.

The best cover crops for cotton, according to Bradley, are wheat and annual rye. “Both of these cover crops are winter hardy, relatively inexpensive and don't require much tillage to germinate — you can just ‘scratch the seed in,’” he says.

Seeding rates should range from 60 to 75 pounds of wheat per acre and from 45 to 60 pounds per acre of annual rye. Planting above these seeding rates can work against you, Bradley adds, because higher seeding populations sap moisture when it's dry and hold moisture when it's wet.

Optimum time for planting wheat and annual rye ahead of cotton is from Oct. 10 until Nov. 10. “As a rule, Dec. 1 is a drop-dead date for planting these cover crops,” Bradley says.

“Fall tillage should be as close to harvest completion as possible to allow for vegetation to come back and get established before it gets cold,” he adds.

According to Bradley, a good cover crop will prevent cotton beds from eroding during the winter and is very competitive with problem weeds such as marestail and cutleaf evening primrose. Cover crops require no fertilization or weed control except for termination in the spring ahead of planting.